‘Three-parent IVF’ was supposed to prevent mitochondrial disease. Studies are raising doubts

The news out of the U.K. last year that eight healthy children had been born to mothers carrying disease-causing mutations in their mitochondria showed the promise of a pioneering reproductive technique known as “three-parent IVF.” The long-anticipated results seemingly showed the procedure, formally called mitochondrial replacement techniques, or MRT, could reduce the risk of babies inheriting sometimes fatal diseases, and raised hopes that other countries, such as the U.S. where MRT is banned,...